Such a typewriter or ribbon cassette is known from German Pat. No. DE-PS 31 53 263. In this ribbon cassette, a window is provided in a wall of a guide arm for the ribbon, through which the ribbon contained in the cassette housing is visible. At the same time, an optical marking is provided above the window on the outer wall of this guide arm. A reflecting light barrier is disposed in front of the marking or of the window, which in the lowered position of rest scans the optical coding and in the elevated printing position scans the ribbon itself through the window. It is possible in this manner to obtain with one and the same sensor information regarding the type of cassette used by means of the optical coding and information regarding the proximity to the end of the ribbon by scanning the ribbon. For this purpose a reflecting foil, for example, may be disposed in the area of the end of the ribbon by means of which the intensity of the reflected light beam is suddenly increased.
Although the known device for the determination of the end of the ribbon is quite adequate, it is nevertheless not satisfactory because in this manner only two different types of cassettes can be recognized, depending on whether the optical coding has been made strongly reflective or weakly reflective.
However, with printers and typewriters having ribbon cassettes there is the definite requirement of collecting very different types of information regarding the type of ribbon prior to the start of the printing process in order to prevent the use of a ribbon not intended or suitable for a desired purpose, or a lack of suitability of the control of the typewriter or printer regarding the ribbon used.
For example, a so-called single-use ribbon can only be used one time and therefore is advanced by a set distance after each printing step which approximately corresponds to the width of the character. With multiple-print ribbons the advance corresponds to only one half or one third of the width of the character to be printed, therefore the electronically controlled advance depends on the type of ribbon used. Additionally, there is a requirement, for example in banking, of only using indelible ribbons, so that it should also be possible to sense whether the ribbon used is one of that type. If it is not the case, the use of such an unsuitable ribbon cassette must be prevented by the control of the typewriter.